Marc has published more than 1000 essays (popular, scientific, and book chapters), 30 books, and has edited three encyclopedias. His books include: the Encyclopedia of Animal Rights and Animal Welfare, The Ten Trusts (with Jane Goodall), the Encyclopedia of Animal Behavior, the Encyclopedia of Human-Animal Relationships, Minding Animals, Animal Passions and Beastly Virtues: Reflections on Redecorating Nature, The Emotional Lives of Animals, Animals Matter, Animals at Play: Rules of the Game (a children's book), Wild Justice: The Moral Lives of Animals (with Jessica Pierce), The Animal Manifesto: Six Reasons For Increasing Our Compassion Footprint, Ignoring Nature No More: The Case For Compassionate Conservation, Jasper's Story: Saving Moon Bears (with Jill Robinson), Why Dogs Hump and Bees Get Depressed: The Fascinating Science of Animal Intelligence, Emotions, Friendship, and Conservation, and Rewilding Our Hearts: Building Pathways of Compassion and Coexistence. The Jane Effect: Celebrating Jane Goodall (edited with Dale Peterson) will be published in 2015.

In 2005, Marc was presented with The Bank One Faculty Community Service Award for the work he has done with children, senior citizens, and prisoners. In 2009 he was presented with the St Francis of Assisi Award by the New Zealand SPCA.